Ancestry Perception Bias in Latin American Admixed Populations

ADHIKARI, K; RUIZ-LINARES, A; BEDOYA, G; BORTOLINI, MARIA CATIRA; CANIZALES-QUINTEROS, S; GALLO, C; GIBBON, S; GONZÁLEZ JOSÉ, ROLANDO; ROTHHAMMER, F; THE CANDELA CONSORTIUM

Congreso; Annual Meeting of the American Society of Human Genetics. San Francisco, CA, USA.; 2012

 CANDELA (Consortium for the Analysis of the Diversity and Evolution of Latin America) is an international collaboration involving researchers from the UK and several Latin American countries (Argentina, Brazil, Chile, Colombia, Mexico and Peru). With its history of extensive population mixture, Latin America in many ways represents a form of natural experiment providing an advantageous opportunity to explore genetic and social aspects related to human biological diversity. CANDELA aims to perform a multidisciplinary study of a wide range of phenotypic, social and genetic data for about 8,000 Latin American individuals. An initial analysis including 40 Ancestry Informative Markers enabled estimation of individual Amerindian, European and African ancestry proportions (using STRUCTURE software) and their contrast with self-reported ancestry as well as with a range of phenotypic and social variables. As expected, we find a significant positive correlation of the genetic and self-perceived ancestries. However, across the region, we observe strong biases in self-perceived relative to genetic ancestry. For example, individuals with low to moderate (0-40%) European genetic ancestry tend to self-perceive their European ancestry as even lower; while individuals with high (>60%) African or Native American genetic ancestries tend to estimate these ancestries as even higher. There is also significant variation across countries in these biases, as much as 20-30% difference in the genetic v. self-perceived ancestries - in the Mexican or Chilean samples, individuals underestimate their Native American ancestry by about 20%, while in the Brazilian or Colombian samples individuals overestimate their Native American ancestry by a similar amount. Several factors could underlie these biases in self-perception of ancestry. For instance, we find that individuals with darker skin color significantly overestimate their African ancestry. We also find a strong effect of gender - relative to men, women underestimating their European ancestry and overestimating their African ancestry. Overall, we find evidence of a complex interplay of social and phenotypic factors in self-perception of ancestry: while visible traits such as skin color have an important impact, perception of ancestry is also intricately linked with social factors, as evidenced by variation across the countries examined.